I had two emerald crabs who would eat my coral. They went to the sump. I have one in my main tank that keeps to its self ^_^ I have a Sally light foot who grazes on what ever it can find on the rocks but it will leave my corals alone. Just gotta keep an eye out for trouble makers. Crabs are hard to catch once you put them in. You have to be tricky to get them out.

I had a Sally in both of my old 30s. They were harmless for years but after getting really large they each began taking swipes at my fish and they got moved to the sumps. Not easy animals to catch.

Lol i tried catch mine with tweezers each day i caught 1 leg and it pulled away dropping the leg that i grabbed lol after about week and half it had no legs sucked for him but after it ate a mandarin blue hippo and powderblue tang i had enough